Eric's original code to work around TXF offset bugs contained a comment
explaining the problem, which was lost when Chris generalized it to an
IR transformation (in commit 598ca510b8a118c3c7e18b5d031a2b116120e0a6).
This commit adds the original comment to the newer code.
Signed-off-by: Kenneth Graunke <kenn...@whitecape.org>
---
src/mesa/drivers/dri/i965/brw_lower_unnormalized_offset.cpp | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/src/mesa/drivers/dri/i965/brw_lower_unnormalized_offset.cpp
b/src/mesa/drivers/dri/i965/brw_lower_unnormalized_offset.cpp
index c95d7f3..8c59b9e 100644
--- a/src/mesa/drivers/dri/i965/brw_lower_unnormalized_offset.cpp
+++ b/src/mesa/drivers/dri/i965/brw_lower_unnormalized_offset.cpp
@@ -66,6 +66,11 @@
brw_lower_unnormalized_offset_visitor::visit_leave(ir_texture *ir)
void *mem_ctx = ralloc_parent(ir);
if (ir->op == ir_txf) {
+ /* It appears that the ld instruction used for txf does its
+ * address bounds check before adding in the offset. To work
+ * around this, just add the integer offset to the integer texel
+ * coordinate, and don't put the offset in the header.
+ */
ir_variable *var = new(mem_ctx) ir_variable(ir->coordinate->type,
"coordinate",
ir_var_temporary);
--
2.1.2
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